The "king of instruments" has a long history, one which can arguably be traced to the concept of a collection of "fixed-pitched pipes blown by a single player (such as the panpipes)" (Randel 583). The first examples of pipe organs with the basic features of today can be traced to the third century B.C.E. in the Greco-Roman arena; it is said to have been invented by Ktesibios of Alexander and contained "a mechanism to supply air under pressure, a wind-chest to store and distribute it, keys and valves to admit wind to the pipes, and one or more graded sets of fixed-pitch pipes." (Randel 583) These early organs used water as a means to supply air-pressure, hence the use of the terms hydraulic and hydraulis.
Hydraulic organs were in use for several hundred years before the concept of bellows, similar in concept and style to those of a blacksmith, came into use with the organ. Numerous bellows were used to supply air to the wind-chest, often being pumped in pairs by men. The disadvantages of this method of air supply include the lack of consistent pressure, which leads to inconsistent pitch and tuning; also, many people were required to operate the bellows since there were upwards of twenty-four bellows per organ (Hopkins & Rimbault 35). Also, with organs of this size, the bellows took up large amounts of space, thus forcing the organ to be located in a fixed place, such as a church.
Up until the eleventh century (approximately), pitch and range of organs were extremely limited, mainly in part to the lack of a any style of keyboard. Keys of a sort were introduced around this time, though not in the manner we are accustomed to. "The earliest keyboards were sets of levers played by the hands rather than the fingers." (Randel 428) They looked similar to large rectangles " an ell long and three inches wide" (Hopkins & Rimbault 33) and were played by pushing on them with a hand, although some were large enough that one might need to step on them. While allowing no real technical dexterity, they were sufficient to play plain-song and chant melodies, particularly with the use of more than one player. As time progressed, the keys became smaller and more numerous until they began to resemble the modern keyboard (except for range) in appearance ca. 1400.
While these large early organs were used in limited fashion in churches, many of the organs of the twelfth and thirteenth centuries were known as portatives or regals. Portatives were small enough to be carried and played by a single person, one hand playing the keys and the other operating a single bellow. Due to the size limitations of portative organs, their range did not usually exceed two octaves; their use was to play plain-song and chant melodies, usually in processions. Similar to a portative, but larger, was the positive organ. " Positives were larger, standing on a table or the floor. They were played with both hands, had a larger compass, and required a second person to operate the bellows, of which there were usually two." (Randel 485) The positive was sometimes added to a larger, stationary organ and joined to the larger's keyboard (two manuals), with the positive being located in front of the larger organ with the organist located between them. (Hopkins & Rimbault 42-3)
Up until this time, organs did not possess pedals. The pedal is generally attributed to a German named Bernard, organist to the Doge of Venice. It is thought that while he did not actually create the pedal board, he improved upon it to the point of being able to assign its creation to him, making it similar in concept to modern pedal boards only with a smaller range. (Hopkins & Rimbault 45-46)
With the addition of the positive to the large organ, one began to have two sets of pipes associated with an organ. These two sets of pipes allowed there to be two distinct tones, similar to stops, to be produced from one organ, though they could not...